Academic not for but against King Edward? (9)
I believe the answer is:
confessor
'edward?' is the definition.
(I've seen this before)
'academic not for but against king' is the wordplay.
I cannot quite understand how this works, but
'not' could be 'con' (I've seen this in other clues) and 'con' is found in the answer.
'king' could be 'r' (abbreviation for rex, king in Latin) and 'r' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for confessor that I've seen before include "One listens to the sins of others" , "man who tells all?" , "Priest who hears sins" , "One who admits to sins" , "One admitting sins" .)